Method for excavating an underpass beneath an existing roadway

ABSTRACT

The invention relates to a procedure whereby an underpass may be dug out from a section of earth over which there already is a roadway. Pillars are constructed into the ground alongside the existing roadway and a superstructure is supported therefrom spanning the existing roadway. This superstructure is then utilized to support the load normally borne by the existing roadway and excavation for the underpass is then carried out.

[451 Oct. 29, 1974 United States Patent [191 Hirsch mmmmmmm l m m" mws an mw m m dw w nO Mr. C urhaoee SBBBBRLH Goldsborough...................

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[22] Filed: July 14, 1972 a Primary Examiner-Nile C. Byers, Jr.

21 Appl. No.: 272,031

Attorney, Agent, or Firm-Stevens, Davis, Miller & Mosher [30] Foreign Application Priority Data July 19, [971 Switzerland......................

[57] ABSTRACT The invention relates to a procedure whereby an un- [52] US. Cl. 14/77 [51] E01d 19/02 73, 23; 52/742,

I t Cl derpass may be dug out from a section of earth over which there already is a roadway. Pillars are constructed into the ground alongside the existing roadway and a superstructure is supported therefrom spanning the existing roadway. This superstructure is then utilized to support the load normally borne by the ex- [58] Field of Search........ 14/77, 75

isting roadway and excavation for the underpass is then carried out.

S T N m m m m mT ks e D E W N U N 5 14/75 1 4/75 7 Claims, 6 Drawing Figures 48,530 7/1865 l89,020 4/1877 Colby......... 534,032 2/l895 Clymer PATENTEDUCI 29 I974 SHEEY 10F 2 FIG.1

./ r" IHlIIII LFII IJIII'I II I IHIIIIIITI lllllllllllllllll FIG. 2

PATENTED 11m 29 1974 I SHEET 2 OF 2 FIG. 5

FIG. 4

FIG. 6

METHOD FOR EXCAVATING AN UNDERPASS BENEATH AN EXISTING ROADWAY This invention relates to a method for constructing an underpass beneath an existing overhead roadway.

Normally, the need to maintain traffic in the existing overhead roadway presents serious problems relative to the simultaneous excavation of the underpass. Heretofore the following expedients have been adopted in such circumstances:

a. the upper roadway traffic has been re-routed during the underpass excavation;

b. the construction of the underpass has been executed in stages;

c. temporary bridges have been employed; and

d. construction has been executed adjacent to the final location and then laterally shifted.

The foregoing expedients entail considerable cost and impede the overpass traffic over fairly long periods of time.

This invention is directed to a method whereby an underpass may be constructed while maintaining traffic on the overhead roadway at less cost than permitted according to construction techniques.

An object of the present invention is a procedure for constructing a passageway underneath a pre-existant traffic roadway and is characterized in that pillars are sunk into the ground and that at least part of the upper roadway load is supported by said pillars before the excavation for the lower pathway is undertaken.

The superstructure of the upper roadway will rest on longitudinal springer structures which are placed on the pillars. As seen further below, the superstructure can be constructed rapidly.

The main excavations will be made following the erection of the superstructure, and they will be easy to carry out, without hampering the upper roadway traffic. The pillars will facilitate the shoring operations.

One manner of construction, and one variation of the procedure will now be described with reference to th attached drawing, where:

FIG. 1 is a top view of a railroad embankment that is to be crossed by an underpass. The first work stage is shown, that is, the construction of the foundations and pillars;

FIG. 2 is a section view taken along line lI-II of FIG. 1, showing the foundations and pillars of the first stage and also the longitudinal springers of the second stage;

FIG. 3 is a fragmentary view of FIG. 2, and enlarged, showing same at a further work stage;

FIG. 4 is a fragmentary longitudinal section showing other stages in the procedure (section along line lVlV of FIG. 1);

FIG. 5 is the same section as in FIG. 4, however after completion of construction; and

FIG. 6 is a section similar to that of FIG. 3, showing a variation in procedure application.

Description will now be provided of how an underpass through the embankment of a railroad 2 is achieved. The underpass may be intended, for instance, for a road sloping along line 3 of FIG. 2. The roads width corresponds to the distance between the two straight lines (dashed) in FIG. 1.

One begins by digging four wood-shored pits of which the bottoms reach at least down to the level of the lower platform (LP); they must rest either on solid ground or on rock. Depending on circumstance, the

2 pits may be replaced by other excavation methods such as three-sided ones if the location is an embankment for instance. The foundations are poured into these pits and then pillars 4 are constructed, for instance of reinforced concrete. These pillars may be made of other materials, for example, metal. Depending on circumstances, the pillars may be replaced by sunk or driven piles; in that case the wood-shored excavations and the foundations are omitted.

Once the pillars have been emplaced, two longitudinal springer structures 7 are constructed (FIGS. 2 and 3), which may be of reinforced concrete; metallic construction also is applicable.

The drawing shows only four pillars, but it is obvious that their number may be increased if the LP is large. If the spans are appreciable, each springer structure will be supported by at least three pillars. If the upper pathway is big and comprises several tracks, the number of longitudinal springer structures shall be increased.

The operations described so far in no way hamper the traffic on track 2, provided the pillars and the springer structures be out of the way of the railroad car loading gauges. These operations may be programmed and interrupted without interfering with traffic or affecting safety.

The next stage, namely, laying the superstructure, must be carried out quickly and preferably during nights, because its requires the temporary removal of the railroad track. It consists in removal of track 2 removal of ballast 8 and of terrain between springer structures 7,

emplacing prefabricated components 9 that make up the superstructure; these components rest by their ends on springer structures 7 and therefore they are transverse beams, replacing the track on temporary supporting blocks 10 resting on components 9.

Trains cannot run during this stage which, in this case, requires no more than 6-7 hours.

The duration of traffic stoppage may be reduced by carrying out in steps the operations above and over several periods when the trains are not scheduled to run. The procedures flexibility allows many combinations in this sense.

The following operations will take place mainly at night, during the scheduled gaps in railroad runs:

manufacture of the emplacement bed for the prefabricated components on the springer structures. It may be made by means of rapid-setting synthetic resin mortar. A special device will be used to pour this bed when components 9 shall already have been emplaced; joining components 9 to each other, for instance by means of a rapid-setting synthetic resin mortar. Depending on circumstances, the bonding between prefabricated components may be reinforced by tie-rods, pre-stressed or not. water-proofing the upperside of the superstructure and the inner sides of the springer structures, the water-proofing material being protected by an appropriate sheating; removal of the supporting blocks, emplacement of ballast; and emplacement of protection barriers.

These operations may be undertaken in stages and with such interruptions as are desired, without therefore adversely affecting traffic and the quality of the work.

The framework of the bridge at this stage having been thus completed, the railroad traffic proceeds as if there were no construction. Then one proceeds with full-scale excavation underneath the superstructure. The main excavation will be in the form of an oblique flank pit as shown by line 12 in FIG. 4. Then proceeding from top to bottom, the lateral passageway flanks will be cleared and the ground will be shored by such means as reinforced concrete planks 13 which will be fastened to pillars 4 as the excavation progresses. FIG. 4 shows one may progress in stages, emplacing planks 13 from top to bottom, lines 14 and 15 showing the successive clearing stages for the lower passageway.

If required by the nature of the terrain for example, due to the danger of a cave-in, ground consolidation by injection may be appropriate before excavating laterally.

Depending on the situation, other lateral excavation methods may be used, for instance by vertical in lieu of horizontal sections, or by making use of vertically emplaced earth sustaining means, etc. Also, in lieu of shoring means 13, one may directly undertake pouring concrete in successive sections. After the pillars have been cleared, they may eventually be covered, even reinforced. This would be especially the case if they have been made initially of metal or are in the form of concrete piles.

To complete the construction, as shown in FIG. 5, a draining jacket 16 will be placed together with a wall 17 against the lateral sides. Lastly, the construction will be finished by preparing the ground of the lower passageway either for a highway or for one or more railroad tracks, etc.

It will be noted that the construction following framework completion including the superstructure may be concluded regardless of the traffic on the upper pathway.

One will further observe that the main excavations are undertaken only after the framework, and notably the pillars, are in place. Therefore, the excavations are facilitated because of the ease of shoring. Shoring provides hard locations for the purpose of hooking up. The safety attending construction therefore is very good.

If traffic interruption of several hours cannot be tolerated, one may make use of the procedure as described as a whole, but modifying the conception of the superstructure. This variation is illustrated in FIG. 6.

The pillars 4 and springer structures 7 are constructed in the same manner as for the first execution of the procedure. When these components are finished, the ballast 8 is removed from track 2 so as to allow inserting temporary metallic springer structures 19, which are 2-3 m apart and the ends of which rest on springer structures 7, underneath the sleepers. The track must be reinforced by bundles of rails 11 or by shaped-profile iron bars. This operation may be undertaken in stages and betwen train passages.

Once these temporary beams 19 are in place, the excavation proceeds fully underneath the bridge. Preferably the superstructure will be a solid slab. However, a prefabricated one may also be considered. Normally, the coffering may be erected after excavation, and the concrete may be poured between metal beams l9. The

slab will be water-proofed and protection for waterproofing will be installed, then the ballast will be put back and beams 19 will be removed. Construction will be completed as described above with reference to FIGS. 4 and 5.

Obviously the procedure may also be applied if the upper pre-existing pathway is a road in lieu of a railway. The different operations that were described will occur in the same order, the only modifications occurring being those due to the different support-conditions for the traffic pathway.

The procedue may also be used when the overpass is still without traffic. In such a case, in lieu of starting with excavating, then constructing the supports and the superstructure as for a traditional bridge, it will be often preferable to make use of the initial presence of the terrain in order to construct the bridge framework. Further, as was seen above, it may be easier to excavate because of the frameworks presence which will serve as a butting point to the shoring means. Thus one may first of all lay the foundations, then construct the pillars and lastly the longitudinal springer structures. Then, the terrain will be removed so as to emplace bridge superstructure which is made up of either prefabricated components or of reinforced concrete poured on the spot; the cofferings then may be directly mounted on the partially cleared ground.

Manufacturing these cofferings will be easier and swifter than if excavation were completed.

The described procedure therefore may be applied fairly generally. It simplifies work when a bridge superstructure must be made at a site where the terrain, initially filled up, must be dug up for setting up a lower pathway.

Again, if the upper pathway is without traffic, one may slightly modify the procedure in this sense: the upper part of the bridge no longer is necessarily constituted by longitudinal springer structures that are connected by a superstructure. This upper part may be made up of reinforced concrete (solid slab, caisson slab, semi-solid slab etc.) which makes use of the raised earth platform as a work area. As in the preceding cases, this upper part will rest on previously built pillars buried in the ground.

It should be observed that in every case when reinforced concrete was mentioned, such term also encompassed the prestressed kind. We assumed reinforced concrete construction in our illustrations, but the procedure may be applied as a whole to constructions making use of other materials, for instance, metallic ones.

What is claimed is:

l. A procedure for constructing an underpass crossing a roadway running on the ground, said underpass extending underneath said roadway, comprising:

constructing a plurality of pillars into the ground, on

both sides of said roadway, the distance between two end pillars located on the same side of said roadway being at least equal to the desired width of said underpass,

constructing springers parallel to the upper roadway and resting on the upper end of said pillars, said springers being outwardly of a predetermined traffic gauge necessary for said upper roadway, placing a superstructure on said springers, said superstructure comprising transverse beams arranged side by side and having their ends resting on the springers, then completing the roadway portion on said superstructure, said superstructure emplacement and roadway portion completion being carried out step by step,

proceeding with a main excavation under said springers and said superstructure,

proceeding with the lateral excavations, said lateral excavations being carried out step by step with pro gressively strengthening the side faces of the underpass from the level of said springers down to the level of a lower platform of said underpass, and completing said lower platform.

2. A procedure according to claim 1, comprising sinking said pillars in the ground and finishing said pillars after completion of said excavations in order to constitute the constructions final pillars.

3. A procedure according to claim 1, comprising driving said pillars in the ground and finishing said pillars after completion of said excavations, in order to constitute the constructions final pillars.

4. A procedure according to claim 1, comprising constructing said pillars of metal components and finishing said components after completion of said excavations in order to constitute the final construction pillars.

5. A procedure according to claim 1, comprising constructing said, pillars of metal components and modifying said components after completion of said excavations in order to constitute the final construction pillars.

6. A procedure according to claim 1, in which said superstructure is a temporary metallic superstructure and said temporary superstructure is completed after completion of the excavations.

7. A procedure according to claim 1 in which all of the pillars are made together in their final form in previously dug pits and wherein said pillars reach a solid underground. 

1. A procedure for constructing an underpass crossing a roadway running on the ground, said underpass extending underneath said roadway, comprising: constructing a plurality of pillars into the ground, on both sides of said roadway, the distance between two end pillars located on the same side of said roadway being at least equal to the desired width of said underpass, constructing springers parallel to the upper roadway and resting on the upper end of said pillars, said springers being outwardly of a predetermined traffic gauge necessary for said upper roadway, placing a superstructure on said springers, said superstructure comprising transverse beams arranged side by side and having their ends resting on the springers, then completing the roadway portion on said superstructure, said superstructure emplacement and roadway portion completion being carried out step by step, proceeding with a main excavation under said springers and said superstructure, proceeding with the lateral excavations, said lateral excavations being carried out step by step with progressively strengthening the side faces of the underpass from the level of said springers down to the level of a lower platform of said underpass, and completing said lower platform.
 2. A procedure according to claim 1, comprising sinking said pillars in the ground and finishing said pillars after completion of said excavations in order to constitute the construction''s final pillars.
 3. A procedure according to claim 1, comprising driving said pillars in the ground and finishing said pillars after completion of said excavations, in order to constitute the construction''s final pillars.
 4. A procedure according to claim 1, comprising constructing said pillars of metal components and finishing said components after completion of said excavations in order to constitute the final construction pillars.
 5. A procedure according to claim 1, comprising constructing said pillars of metal components and modifying said components after completion of said excavations in order to constitute the final construction pillars.
 6. A procedure according to claim 1, in which said superstructure is a temporary metallic superstructure and said temporary superstructure is completed after completion of the excavations.
 7. A procedure according to claim 1 in which all of the pillars are made together in their final form in previously dug pits and wherein said pillars reach a solid underground. 